US3152372A

US3152372A - Method and apparatus for producing improved alloy metal

Info

Publication number: US3152372A
Authority: US
Inventors: Robert K Hopkins
Original assignee: Firth Sterling Inc
Current assignee: Firth Sterling Inc
Priority date: 1959-12-10
Filing date: 1959-12-10
Publication date: 1964-10-13
Anticipated expiration: 1981-10-13
Also published as: GB925653A

Description

Oct. 13, 1964 R. K. HOPKlNS 3,152,372

METHOD AND APPARATUS FOR PRODUCING IMPROVED ALLOY METAL Filed Dec. 10, 1959 5 Sheets-Sheet l INVENTOR. Robert K. Hap/ins HIS A TTORNE Y5 Oct. 13, 1964 R. K. HOPKINS 3,152,372

METHOD AND APPARATUS FOR PRODUCING IMPROVED ALLOY METAL Filed Dec. 10, 1959 5 Sheets-Sheet 2 INVENTQR. Robe/f K. Hapklns HIS ATTORNEYS R. K. HOPKINS Oct. 13, 1964 METHOD AND APPARATUS FOR PRODUCING IMPROVED ALLOY METAL Filed Dec. 10,

5 Sheets-Sheet 3 4 Raberi m w fi 's iw/icM W H/S A TTORNEYS R. K. HOPKINS 3,152,372

METHOD AND APPARATUS FOR PRODUCING IMPROVED ALLOY METAL Oct. 13, 1964 5 Sheets-Sheet 4 Filed Dec. 10, 1959 R. K. HOPKINS 3,152,372

METHOD AND APPARATUS FOR PRODUCING IMPROVED ALLOY METAL Oct. 13, 1964 5 Sheets-Sheet 5 Filed Dec. 10, 1959 H /5 A 7725/1/15 r:

United States Patent Ofifice 3,152,372 Patented Oct. 13, 1954 3 152,372 METHOD AND APPARATUS FOR PRODUCKNG Iii/ERGVED ALLGY IWETAL Robert K. Hopidns, West New Brighton, Staten Ksiand,

N.Y., assignor to Firth Sterling, Inc., Pittsburgh, Pa,

a corporation of Pennsylvania Filed Dec. 10, 1959, Ser. No. 358,719 6 Claims. (Cl. 226tl) This invention pertains to the making of higher quality alloy metals in ingot form and particularly, to making alloys having improved surface characteristics and a finer grain structure.

Heretofore, many alloys when produced in ingot form have, by reason of their inherent nature, tended to have relatively larger size grains on solidification. For example, austenitic steels tend to have a larger grain structure than ferritic and martensitic types, and thus must be preliminarily forged or worked from ingot to billet form before they can be formed, as by forging, into requisite products such as turbine wheels. In addition, in producing ingots by electrode melting procedures, there has been considerable loss in the metal by reason of the relatively rough peripheral surface produced along the ingot mold; this surface must be removed before the ingot is usable.

My present invention deals particularly With the field of consumable electrode melting where progressive solidification of the ingot metal is involved. It has resulted from the continued need for an improved quality of ingot metal, particularly in making of higher alloy products, such as those used under relatively high temperatures, high stresses and severe operating conditions in connection with more critical stationary and rotatable parts of equipment, such as gas turbine and other utilizations.

In endeavor-ing to provide an improved or smoother surface of ingot to minimize loss of ingot metal and the expense of extensive surface removal operations, I conceived of the idea of rotating the mold with respect to the consumable electrode. I determined that magnetic stirring was not suitable, as it tends to produce an unsatisfactory surface, to give a non-uniform grain and to produce a parabolic shape of the molten metal at the top of the ingot. Relative rotation between the mold and the ingot metal is inherent but is of a type that sets up eddy currents in the surface of the metal. Also, I have found that in a magnetic stirring operation, the electrode has to be maintained at the exact center if a reasonably satisfactory surface condition is to be approached. In this connection, I have determined that it is important to avoid relative motion between the inner wall of the mold and the surface of the ingot, to prevent a parabolic shape of the ingot and to provide it with a substantially planar or flat top surface, not only to avoid coning, but also to assure a substantially uniform grain structure and an outer or peripheral wall that is relatively smooth.

Another factor which I have been able to meet is that of enabling the use of a consumable electrode of any suitable diameter effectively, without damage to the physical and other properties of the ingot produced. I have discovered that best melting conditions are attained by positioning the electrode so that it is within about 1 to 1 /2 inches from the inside wall of the ingot mold. If the distance is shorter than this, the arc tends to jump to the water-jacketed copper mold wall and thus burn it out. Relative rotation between the end of the electrode and the molten metal assures a uniform burnoif of the end of the electrode. On the other hand, in stationary consumable melting, an off-center positioning of the electrode as to the mold wall produces nonuniformity in the ingot and also increases the danger of burning through the mold wall.

i have been able to maintain a good working distance between the inside of the ingot mold and the electrode and, at the same time, use a consumable electrode of any desired diameter by providing relative rotation, such that even a smaller electrode will have an opportunity to effectively melt and maintain the full extent of the upper surface of the ingot in a molten condition, and assure a uniform solidification of the metal as the ingot is built-up.

A further highly important result of my invention has been that relative rotation produces not only a fully uniform grain structure, but one which is of a much finer nature and that makes possible the elimination of conventional preliminary forging steps. Further, the grain structure produced in accordance with my invention is not only such that it can be directly forged into a final product, such as a turbine wheel, but is also such that its grain is non-directional, thus giving improved strength qualities in the ultimate product in both transverse and longitudinal directions.

It thus has been an object of my invention to devise new and improved procedure for making high quality alloys and alloy products;

Another object has been to develop apparatus for carrying out my procedure;

Another object of my invention has been to provide a procedure for producing a finer grain ingot by consumable electrode melting in which the ingot is built-up by progressive solidification and has such a nature and quality that an improved smoothness of peripheral surface and a uniform finer grain structure is produced in the ingot;

A further object of my invention has been to employ relative rotation between a consumable electrode and an ingot mold in such a manner as to greatly improve the quality and structure of the ingot produced;

A still further object has been to provide an ingot which, when cut to a suitable size, may be directly employed in place of a preliminarily forged and conditioned billet for producing products that are subjected to high stresses in their utilization;

These and other objects of my invention will appear to those skilled in the art from the description thereof.

In the drawings,

FIGURE 1 is a vertical view in elevation of apparatus devised to carry out my procedure, including a rotating ingot mold and electrode supporting and positioning means to facilitate the insertion of a second consumable electrode when a first electrode has been substantially used up or consumed in making an ingot;

FIGURE 2 is a reduced, somewhat diagrammatic plan View of the apparatus of FIGURE 1, showing how the mold may be swung between two operating positions;

FIGURE 3 is a horizontal section on the scale of and taken along the line IIIIII of FIGURE 2; this view shows details of suitable raising and lowering means for the electrodes;

FIGURE 4 is an enlarged vertical section of the mold of FIGURE 1, as partially broken away through its shell or wall; this figure illustrates details of my improved construction, particularly from the standpoint of means for conducting electric current to the revolving mold;

FIGURE 5 is a macrograph taken along the surface of the longitudinal axis of a prior art (static) ingot of Discaloy analysis and FIGURE 6 is a similar macrograph of a fine grain ingot of the same Discaloy analysis as produced in accordance with my present invention; the surfaces of both ingots have been ground off the same amount to better show the grain structure;

FIGURE 7 is a top disc or cross section macrograph 3 through the ingot of FIGURE 5, and FIGURE 8 is a similar top disc or cross section macrograph through the ingot of FIGURE 6 showing its uniformity and improved nature.

In accordance with my invention, I turn an ingot mold with a relatively slow speed of rotation which is effective while ingot metal is being melted and progressively solidified in the mold and while the metal is being supplied by the consumable electrode and by any desired additions to the melt during the operation. The rotation is accomplished at a speed below that at which centrifugal force becomes strongly efiective or below a speed which tends to cause a pronounced parabolic shaping or outward flinging of the molten metal surface, adjacent to or at the top of the ingot. This speed may be a constant one throughout the casting operation, and may be accomplished (as to conventional mold sizes) by rotating the ingot metal being formed at about 50 to 200 surface inches per minute, with an optimum of about 100 surface inches per minute. For example, I find that a speed of about 1 to 4 (2% optimum) rpm. is suitable for a or 16 inch inner diameter of mold. A speed of an optimum of about 3 rpm. is suitable for an 11 inch inner diameter of mold and of about 6 to 7 r.p.m. for a 9 inch inner diameter of mold. As an optimum, I employ a movement that does not disturb a relatively calm and non-turbulent condition of the molten metal, if such condition is to be maintained during the ingot forming (as in a slag melting process).

During this rotation, the molten metal tends to follow the mold and it is my theory that as solidification progresses, larger grains are prevented from growing or germinating by virtue of the relative movement (disturbance) between the solidifying portion of the ingot along the solidus face and the liquid metal of the molten pool. The presence of the current discharging or arcing end of the electrode (which is stationary except for its vertical movement because of burn-off) and the inertia of the molten metal (and slag blanket, if used) tend to prevent the molten pool from attaining the same rotational speed as the mold or the solidified portion of the ingot and thereby disturbs the metal at the instant of solidification, thus producing a uniformly fine grain structure throughout the Zingot. The molten metal thus rotates at substantially the rate of, but slightly slower than the solidified metal in the mold, for example, A; to /2 of a revolution less, using a 9 inch diameter of mold at about 6 to 7 rpm.

My procedure has been found to improve ingot quality and to produce a uniform, unidirectional and finer grain structure. In addition, the outer surface of the ingot is much smoother than produced by conventional procedure, and thus requires a minimum of conditioning. I have demonstrated the efiectiveness of my method on consumable electrode melting under a slag and because of the principles developed, it is also applicable to casting in vacuum induction, vacuum are or air melting operations.

Thus, in accordance with my present invention, I have been able to produce a uniform and finer grain structure in an ingot, such that it may be directly used in place of a conventionally forged billet and, as such, is better than a billet because of its non-oriented flow lines or unidirectional properties and, as such, may be worked, for example, by forging-shaping operations into a finished part, and one whose properties in all directions are improved over those of a conventionally forged billet of the same alloying or metal content.

.Further, I have successively employed very small size consumable electrodes, as well as extremely large electrodes and electrodes of various shapes, such as square,

. cylindrical, etc. In accordance with my process, alloying additions can be added during the formation of the ingot and still maintain a uniform structure by avoiding richer area concentrations at points of feed. It is my theory that the fine grain structure results from friction and slide between the grains during a disturbed solidification which amounts to a working while the metal is in a molten or semi-molten condition. Further, I have been able to obtahi a more uniform and an increased rate of cooling and solidification of the ingot metal which furthers the improvement in the grain structure.

Although my process is adaptable for making alloys of many .types, it is particularly advantageous where the alloy content is such as to normally produce a relatively large grain structure in a solidified ingot. Thus, my procedure is particularly applicable for producing higher alloys where specification requirements are relatively rigid. l have been able to do so at a much lower cost, by reason of the elimination of previously-required preliminary forging steps to condition the grain structure of the metal. I avoid the disadvantageous features of a magnetic-flux method, namely, the non-uniform grain and bad surface erlects thereof, and I have been able to maintain a desirable melting rate without throwing-up the metal and/ or slag surface.

In accordance with the slag melting application of my procedure, the end of a consumable electrode is submerged in the slag, the slag is ionized, and a relatively soft and constant arc or current flow is provided beneath its surface. If a peripheral speed in the nature of an effective centrifugal speed is attempted, a throw-up or centrifugal effect will be produced, tending to cause a cavitation adjacent the center of the slag and, it carried sufficiently far, will expose the end of the electrode and produce a hard, faster melting and somewhat irregular type of are or current flow, such as may be encountered in air or vacuum melting. Also, where my procedure is applied to slag as well as consumable air or vacuum types of melting, an effective centrifugal speed must be avoided to prevent cavitation of the molten metal, an onion effect in the solidified ingot metal, a larger grain size due to slower solidification, and a poor peripheral surface.

Relative speed of rotation between the consumable electrode (or electrodes) and the ingot metal and mold has been found to be independent of the metal analysis, but must be controlled from the standpoint of the diameter of the mold or of the ingot metal, in the sense of an effective relatively slow peripheral speed of the metal being solidified, such that eddy currents are avoided with their attendant bad surface efiects as to the ingot metal. I thus employ a higher rotating speed for a smaller size mold than for a larger size mold (to maintain substantially the same peripheral speed), but one that is below (as a maximum) a speed that for a given size of mold constitutes an effective centrifugal speed as to the molten material. 7

Rotation makes possible an effective use of smaller or a plurality of electrodes that do not have to be centered better grain structure than such a forged billet, due to the non-directional nature of the structure, whereas the forged billet has its greater strength in the direction of its working. In my process, the mold and molten ingot metal rotate substantially together, a further assurance in avoiding disadvantageous surface eddy currents in the molten metal. The consumable electrode (or electrodes) can be advantageously positioned off-center as to the vertical axis of the ingot metal and near the mold wall to, among other things, avoid a localized enriched area adjacent the electrode, provide a uniform distribution of the metal in the molten pool, and wash the metal surface as well as the slag blanket (if used) smooth. No flow lines are produced in the solidified ingot metal.

In carrying out my invention, I find that I can employ the same input as in a stationary or static operation and f tl that the rate of melting is, as before, directly proportional to the are or current flow from the end of the electrode to the molten metal. A shallow pool can be provided and the operation conducted in substantially the same time period as in a static operation. As a result, I have found that my rotating operation can be accomplished at substantially the same production rate with substantially the same operating costs, as in a static operation, to produce an ingot which is at least the equivalent to a twoor three-step preliminary forged billet, thus eliminating the necessity for such prelirninary operations and materially decreasing the cost of the starting shape for forming a desired type of product. That is, standard final forging and shaping operations can be accomplished on an ingot produced in accordance with my invention the same as in the last die-forging steps of a conventionally forged billet to directly form a product, such as a turbine wheel therefrom, Without danger of tearing the metal, and to produce a product which is even better in its strength characteristics than that produced by a conventionally forged billet. In addition, I minimize top crop and surface grinding so as to provide a much better yield from a given ingot than heretofore possible.

In employing my procedure, I contemplate the use of a stationary stand, support or table for the ingot mold or cooling means that provides a bounding area for the molten metal pool, the solidifying and the solidified ingot metal. The stationary stand carries a rotating table, support, or platform on which the mold is directly mounted for rotation therewith. Since I contemplate a continuous (although relatively slow) rotation of the mold, flexible electric connections are unsuitable. Thus, it has been necessary to provide some suitable rotating electrical contact means between the rotating mold or between its rotating table and a stationary conductor means, such as a bus bar, or the stationary support stand or table. In this connection, a contact sleeve may be carried by the rotating table or the mold to ride over a circular bus bar carried by the stationary means or, vice versa. Also, commutator or slip ring means, such as used in motors, may be utilized.

However, I have found that a highly eflicient type of rotative connection is needed in view of the higher currents used in a consumable electrode arc-melting operation and, as a result, have developed an improved type between the rotating mold and stationary current supplying means. I have been able to devise a connection that eliminates spark ng and the wear and tear of sliding, commutator, and other types of connections, as Well as loss of power due to voltage drop.

I have been able to develop a highly etfective means for this purpose which utilizes a liquid conductor, such as a liquid metal in the nature of mercury. The conductor material may be carried in a circular trough within which an electrical contact element that is carried by the mold structure or its rotatable table, moves or rotates. In accordance with such a construction, I have been able to minimize voltage drop to about one-quarter of a volt, to entirely eliminate sparkng, and to provide a highly eihcient and efiective current supply connection between parts that rotate relative to each other. A connection of my construction makes possible cooling the parts and the conductor material, so as to always maintain the contacts at a maximum eficiency and irrespective of ambient temperature conditions and the heat given off by the mold during the melting operation.

In employing my procedure, I also contemplate the use of a feed pipe 25 or 25' (see FIGURE 1) at the top of the melt which may be used to continuously replenish and renew a slag cap or blanket a (if employed), and to provide any desired minor alloying or metal additions to bring the melt up to the desired composition content.

Further, in accordance with my present invention (see FIGURE 1), I employ a consumable electrode 10 or 1t) which has been previously fusion-formed (e.g., an ingot), has substantially the desired metal alloy content for the cast ingot body to be formed, and which, because of the nature of its structure or its content of inclusions, etc., is not of the desired quality for the final product. The metal electrode body 10 is positioned with its end extending within the ingot mold A or the bounding area defined by the cooling medium, and electrical current is discharged from such end to form a molten pool b within the mold from progressively melted particles.

The metal of the pool I) is progressively cooled and solidified at substantially the same rate as particles of metal are supplied to it by the fusing-off of the electrode end. That is, molten particles are continued to be removed from the end of the electrode body to maintain the pool While the solidification progresses, by an action that starts from the bottom of the pool or mold and progresses upwardly. The cooling action is controlled by the amount and temperature of the cooling medium, such as water, which is circulated through the jacketed or concentric shell wall of the mold A, so as to solidify or build-up the alloy metal into ingot metal c of cast form from a point remote from the electrode body or adjacent the bottom of the pool b, at substantially the rate of formation of the pool or removal of molten particles from the body. Continuous, relatively slow speed, rotative movement is imparted to the molten, solidifying, and solidified ingot metal Within the mold relative to the electrode body during the above ingot-forming steps, and until a cast ingot of the desired length has been built-up. If the electrode body being currently used is substantially consumed, then a second electrode body It) is immediately moved or lowered to a Working position within the mold and the operation continued.

During the formation, a relatively soft arc or current fiow and relatively slow melting rate are preferably employed to avoid spattering and to accomplish a full levitation or upward movement or removal of impurities, such as non-metallic inclusions and gases, from the metal of the pool that is being furnished by the consumable electrode body 10 or 19' and further, in such a manner that any previous metallic inclusions, such as of higher melting point alloy materials, are fully fused and melted to become a uniform absorbed portion of the molten pool. The rotation of the metal in the ingot which is accomplished by rotating the ingot mold or the bounding or supporting area or means, is at a relatively slow speed, such that the top surface of the molten pool will be substantiaHy undisturbed from the standpoint of peripheral buildup by reason of the rotative movement or in other words, and such that an effective centrifugal force action will not be imparted to the metal and particularly, the metal of the molten pool. The rotative action as to the solidifying metal is such that an internal action will occur in accordance with which its grain structure is reduced to a size at least corresponding to that of a conventional ingot that has been previously preliminarily forged, but with a resultant directional type of structure.

when a molten slag or flux blanket a is employed for best results, it acts as a cover over the surface of the molten pool b, and the heat-producing current flow across the gap and designated as an arc d formed by the consumable electrode body, electrically ionizes the blanket. The end of the electrode is positioned to extend into the slag blanket but in a spaced relationship to the molten pool. Such a slag blanket may be employed to take-up impurities from the melt and to improve and hold the heat of the molten pool and particularly, to further a relatively slow melting and provide an improved peripheral surface in the final ingot body, as cast. The ingot body formed will have a thin protective egg shell enclosure of slag along its peripheral surface which may be readily removed to leave a good surface that does not require extensive metal removal, as compared to a corn cob or pineapple type of peripheral surface.

The principles of my present invention apply to other melting procedures, such as those above-mentioned. However, best results are attained by using a slag blanket from the standpoint of making possible a relatively quiescent type of melting action, of minimizing top and bottom cuts in the ingot, of the elimination of macro inclusions, segregation, etc., and from the standpoint of a better peripheral surface on the ingot. It is also believed to be apparent that faster melting or solidification rates, such as involved in air, vacuum or induction melting, may also be employed with the attainment of improved results, such as a better size and nature of grain structure in the resultant ingot.

By way of illustration, I have shown suitable apparatus that may be employed in carrying out my invention. With particular reference to FIGURES l and 3, the ingot mold A is shown positioned on a rotating table or stand B which is, in turn, rotatably carried by a support or stand C that is stationary with respect to rotation of the table B. The rotating table B has a hollow shaft extending through the support C for rotative actuation by a motor-driven mechanism D.

Electrode body 10 is shown mounted to extend downwardly from an arm or wing of an overhead support or suspension structure E which is adapted to suspend the electrode in an aligned, centered or off-centered relationship with the ingot mold A, to progressively lower or feed the electrode into the mold as its end is melted off during the forming of an ingot, and to raise the electrode or its melted-H stub out of position within the mold to facilitate the melting operation, where one electrode 13 has been used up before an ingot has been completely formed in the mold. I also show a separate support or suspension structure E whose electrode may be suspended in an up position ready for lowering through the opening in the ingot mold into an arcing position when the electrode 10 being used has been raised and the mold A has been swung out of an aligned position with it to an aligned position with the auxiliary electrode (see FIG- URE 2 The separate support structure and operating mechanisms for both of the electrodes 10 and Ill is of similar construction, although one is positioned in a spaced relationship with the other such that the mold A may be swung between them.

The support and suspension structure E (or E) has a wing or arm 12 that extends radially or transversely-outwardly and terminates in a suspension collar 12a (see FIGURE 1) against which a welded-on, enlarged, electrical connection head 11 for the electrode 10 is adapted to suspend the electrode. In utilization, the head 11 of each electrode may be connected by a flexible means, such as a braided conductor cable, to one potential side of a conventional source of electricity, such as a direct current generator. Current of opposite potential may be supplied by an electric connection from the other side of the source, either by a bus bar or by a connection to a flexible metal conductive inlet tube (such as of copper) such as 37, of the stationary stand or table C, and through an electrically conductive fluid medium, such as mercury liquid, to the rotating table B and thus, to the ingot mold A and the metal being processed therein, so as to support the heat-producing current flow or are across the gap formed between the end of the electrode 10 and the metal.

The inner or opposite end of the wing or arm 12 terminates in a pair of vertically spaced-apart slide mounting sleeves or collars 12b that are carried slidably on a square or rectangular vertical column 13. The column 13, as shown particularly in FIGURE 1, is positioned to extend at its lower end within a fixed stand or base 16. The column 13 is secured to project upwardly from the stand 16 and has a mount 13b for rotatably receiving a pulley over which a raising and lowering cable 14 passes. It is noted that the upper end of the cable 14 is secured at 14a to the structure E adjacent one of the sleeves 12b and'extends downwardly along the column 13 to, at its lower end, interleave over a winding drum 17 (see also FIGURE 2) to which such end is secured.

As shown particularly in FIGURE 2, the drum 17 is actuated for raising and lowering movement by a reversible electric motor 19 through a gear set 18. The motor, in turn, has a magnetic brake 2% for retaining the drum 17 in a desired position. The gear set 18 actuates the drum 17 at a controlled down feeding rate corresponding to the melting rate of the electrode within the ingot. The motor 19 may be actuated in an opposite direction to raise the wing 12 to an upper ready position, such as shown for the second or auxiliary electrode 10 in FIGURE 1. It is noted that the assembly of FIGURES 1 and 2 is mounted on an intermediate shelf portion 16a of the stand 16. As shown in FIGURES 1 and 3, the mounting and operating structure B, C and D for the mold A is carried by a swing table 21, so that the mold A may be swung by arm or handle 22 between positions (1) and (2) of FIGURE 2. At position (1), the mold is in alignment with one electrode 10 and in position (2), it is in alignment with the auxiliary electrode 10'. The

swing table is shown pivoted at 23 on a floor-mounted or stationary support plate member 24. In FEGURES 2 and 3, I have shown the handle 22 provided with a spring detent 22a to index with peripherally spaced depressions 24a in the upper face of the member 24, in order to properly locate and hold a desired alignment of the

electrode

19 or 1% within the mold A.

Referring particularly to FIGURE 4 of the drawings, the ingot mold A is shown as comprising a metal inner vertical cylindrical mold side wall 30, an intermediate metal jacketing or shell wall 30a and an outer metal jacketing or shell wall 3012. Cooling fluid, such aswater, is introduced to the surrounding jacketing of the mold A by a side conduit 32, through a side port 31, downwardly along the spacing defined between the outer wall 35b and the intermediate wall Sea, through a port in the lower end of the wall 30a, and upwardly along the spacing. between the walls 36a and 36 and, as warmed fluid, is exhausted through an opposite side port 49 and .a side conduit 41.

The cooling fluid may be introduced through a somewhat flexible inlet conductor conduit 37 and a chest 36 or" the support stand C, through a port in a hollow-cylindrical or tubular, downwardly-projecting, actuating shaft 35 for the rotating table B, upwardly along the inside of the shaft 35 into a bottom chest 34 in the rotatable table B, and through a chest half 33 and suitable side ports and ducts to the side conduit 32. The chest 34 is separated from the cavity of mold A by a bottom wall or plate 34a. In this manner, the bottom of the ingot mold as well as its side walls are subjected to the action of the cooling fluid, so that the rate of flow or its temperature may be controlled to solidify the molten metal that is being formed in the ingot mold at a rate corresponding to its formation from the end of the consumable electrode 10.

It will be noted that incoming cooling fluid passes through the chest 33 that constitutes a semi-circular bottom half of the table B, and that exhausting warm fluid passes through a similar chest 42 at the bottom of the other half of the table. Warmed fluid moves from the chest 42 downwardly through spacing defined between the shaft 35 and an outer concentric cylindrical wall or shaft sleeve 35a, into a chest 44 of the support table C, to discharge through a somewhat flexible outlet pipe or conduit 45 to the fluid circulating system. This system may include means for cooling the water and returning it through the inlet pipe 37; since the cooling fluid passes through a closed system, it is not contaminated and may be reused.

It will be noted that the, shaft 35 as well as the outer shaft sleeve 35a are secured to extend downwardly from the rotating table B and are journaled within and for rotation with respect to the support stand C. The actuating mechanism D is shown as having a chain sprocket that is journaled within the stand or support C and as securely connected by a stud shaft to the hollow shaft 35.

The non-rotatable or stationary stand C, as shown particularly in FIGURE 4, has a radially-outWardly-projecting support shelf or table portion 47 that is secured thereto and which has an electrically-conductive relationship through the stand C or, if desired, through a direct electrical connection from the conductor inlet pipe 37, to present current of one potential to a pair of concentrically spaced-apart and upwardly-projecting, continuous, inner and outer trough walls or conductor flanges 43 and 43a. The flanges or walls 48 and 48a define an upwardly-open conductor trough to centrally receive a downwardly-extending, circular, conductor flange or wall of the rotatable table B. A suitable electrically-conductive fluid, such as mercury liquid 51, is carried by the conductor rough to continuously supply electricity from the flanges 48 and 48a to the flange Slia, to the rotating table B, its mold A, and ingot metal carried therewithin.

An outer, upwardly-projecting circular and concentric flange or wall 48b defines a cooling-fluid trough with the outer conductor flange 43a of the stationai I stand C to receive a downwardly-projecting, outer, sealing flange or Wall 5%) of the rotating table B. Cooling fluid 52 within the outer trough thus serves to keep the conductor medium 51 at an eflicient operating temperature and to also seal it off from atmospheric contamination. Conducting fluid may be supplied to the conductor trough of the table portion 47 through a port therein by flexible piping 49. Cooling fluid may be introduced to the sealing and cooling trough of the table portion 57 by inlet pipe 53 and warmed fluid may be exhausted therefrom through outlet pipe 54; as previously mentioned, these pipes are somewhat flexible and may be connected to a closed, circulating, cooling fluid system.

From the above description of illustrative apparatus suitable for carrying out my invention, it will be apparent that the mold A may be continuously rotated at a suitable speed with respect to the electrode 19 (or during the forming of a cast metal ingot, that an eflicient controlled rate of cooling action may be employed to effect a desired or requisite rate of solidification of molten metal produced by the electric melting operation, and that electric current may be supplied continuously in an effective manner to maintain the are or the heating action of the current flow across the gap and through a high resistance conductor such as represented by a slag blanket, at all times during rotation of the mold. Although I have described a suitable apparatus for this purpose, it will be apparent that other apparatus may be employed without departing from the spirit and scope of my invention, as indicated by the appended claims.

\Vhat I claim is:

1. A method for consumable electrode forming a cast solid-section alloy metal ingot of substantially uniform and finer grain structure corresponding at least to the fineness of a preliminarily forged body within an ingot mold having cooperating side and bottom walls defining a mold cavity therein that is fully horizontally-centrally unobstructed which comprises, providing a previously fused vertically-extending alloy metal electrode body of substantially the desired metal content of the solid-section alloy metal ingot, inserting the electrode body within the mold with its lower end extending vertically-domi- Wardly along the mold cavi applying energizing electric current to the electrode body, progressively fusing-01f alloy metal from the lower end of the electrode body within the mold cavity by discharging electric current therefrom; forming and maintaining a molten alloy metal pool from the fused-off metal of the electrode body within and fully across the horizontal section of the mold cavity, while progressively advancing the end of the electrode body within the mold cavity during the melting operation,

and while cooling the walls of the mold cavity and progressively solidifying the molten alloy metal of the pool upwardly from the bottom wall and forming an alloy metal ingot of solid section; maintaining the lower end of the electrode body in a horizontally ofl-centered relation with respect to the horizontal section of the mold cavity and with respect to the horizontal section of the molten metal pool, continuously mechanically rotating the mold with respect to the electrode body at a relatively slow speed that is below an effective centrifugal rate for the molten metal of the pool, maintaining the molten alloy metal pool during the operation in a relatively quiescent condition without producing eddy currents therein, effecting a slight relative movement between the molten alloy metal of the pool and the progressively solidifying molten metal of the pool to refine the grain structure of the metal of the ingot being formed in a non-directional manner, and effecting the cooling and progressive solidification of the molten metal of the pool within the mold cavity at substantially the rate at which it is fused-off from the end of the electrode body.

2. A method as defined in claim 1 wherein the offcentered relation of the end of the electrode body with respect to the horizontal section of the alloy metal pool is varied during the operation.

3. In apparatus for consumable electrode forming a cast solid-section alloy metal substantially cylindrical ingot of substantially uniform and finer grain structure corresponding at least to the fineness of a preliminarily forged body by employing a previously fused verticallyextending alloy metal electrode body of substantially the desired metal content of the solid alloy metal ingot, a mold having a solid metal ingot forming vertical mold cavity defined by a vertically-extending outer side wall and a bottom wall cooperating therewith, said mold cavity terminating at its upper end in an opening and providing a fully horizontally-centrally unobstructed metal solidifying and metal melting area vertically upwardly from said bottom Wall, means for cooling said Walls to progressively solidify molten metal upwardly and form a metal ingot of solid section from said bottom wall, means for supporting the electrode body above said mold cavity to extend through the opening into an operating position within said mold cavity, means for supporting said mold for rotation about its central axis, means for causing electric current to pass through said electrode body for initiating and maintaining an electric current flow at the lower end thereof to progressively fuse-off alloy metal therefrom and thereby create and maintain a molten alloy metal pool across the full horizontal section of said mold cavity, means for adjusting and maintaining the lower end of said electrode body in a horizontally oficentered relation with respect to the horizontal section of said cavity and thus with respect to the horizontal section of the molten alloy metal pool, means cooperating with said supporting means for said electrode body for progressively advancing said electrode body towards the molten metal pool to maintain the electric current flow during the melting operation, means for continuously rotating said mold about its central axis with respect to said supporting means therefor and with respect to the electrode body during the arc melting of the electrode body at a relatively slow speed that provides below an effective centrifugal force with respect to the molten metal pool and in such a manner that the molten metal pool is maintained in a substantially quiescent condition without surface eddy currents therein, said means for adjusting and maintaining the electrode body in a horizontally off-centered relation carrying said mold, and means carried by said support means and cooperating with said adjusting and maintaining means to latch said mold in a selected position with respect to said electrode body.

4. In apparatus for consumable electrode forming a cast solid-section alloy metal substantially cylindrical ingot of substantially uniform and finer grain structure correspending at least to the fineness of a preliminarily forged body by employing a previously fused vertically-extending alloy metal electrode body of substantially the desired metal content of the solid alloy metal ingot, a mold having a solid metal ingot forming vertical mold cavity defined by a vertically-extending outer side wall and a bottom wall cooperating therewith, said mold cavity terminating at its upper end in an opening and providing a fully horizontally-centrally unobstructed metal solidifying and metal melting area vertically upwardly from said bottom wall, means for cooling said Walls to progressively solidify molten metal upwardly and form a metal ingot of solid section from said bottom wall, means for supporting the electrode body above said mold cavity to extend through the opening into an operating position within said mold cavity, means for supporting said mold for rotation about its central axis, means for causing electric current to pass through said electrode body for initiating and maintaining an electric current flow at the lower end thereof to progressively fuse-oft alloy metal therefrom and thereby create and maintain a molten alloy metal pool across the full horizontal section of said mold cavity, means for adjusting and maintaining the lower end of said electrode body in a horizontally off-centered relation with respect to the horizontal section of said cavity and thus with respect to the horizontal section of the molten alloy metal pool, means cooperating with said supporting means for said electrode body for progressively advancing sm'd electrode body towards the molten metal pool to maintain the electric current flow during the melting operation, means for continuously rotating said mold about its central axis with respect to said supporting means therefor and with respect to the electrode body during the arc melting of the electrode body at a relatively slow speed that provides below an effective centrifugal force with respect to the molten metal pool and in such a manner that the molten metal pool is ma ntained in a substantially quiescent condition without surface eddy currents therein; said means for adjusting and maintaining the lower end of said electrode body in a horizontally otfcentered relation comprising, swing means carrying said mold and cooperating with and pivotally mounted on said support means for said mold to swing said mold with relation to said electrode body, and means for latching said swing means in a selected position with respect to said support means for said mold.

5. A method for consumable electrode forming a cast solid-section alloy metal ingot of substantially uniform and finer grain structure corresponding at least to the fineness of a preliminarily forged body within an ingot mold having cooperating side and bottom walls defining a mold cavity therein that is fully horizontally-centrally unobstructed which comprises, providing a previously fused vertically-extending alloy metal electrode body of substan ially the desired metal content of the solid-section alloy metal ingot, inserting the electrode body within the mold with its lower end extending vertically-downwardly along the mold cavity, applying energizing electric current to the electrode body, progressively fusingoff alloy metal from the lower end of the electrode body within themold cavity by discharging electric current therefrom; forming and maintaining a molten alloy metal pool from the fused-0d metal of the electrode body within and fully across the horizontal section of the mold cavity, While progressively advancing the end of the electrode body within the mold cavity during the melting operation, and while cooling the Walls of the mold cavity and progressively solidifying the molten alloy metal of the pool upwardly from the bottom wall and forming an alloy metal ingot of solid section; maintaining the lower end of the electrode body, the molten metal fused-0E therefrom and the molten metal pool within a protective slag blanket; maintaining the lower end of the electrode body in a horizontally ofif-centered relation with respect to the horizontal section of the mold cavity and with respect to the horizontal section of the molten metal pool, continuously mechanically rotating the mold with respect to the electrode body at a relatively slow speed that is below an effective centrifugal rate for the molten metal of the pool, maintaining the molten alloy metal pool during the operation in a relatively quiescent condition without producing eddy currents therein, effecting a slight relative movement between the molten alloy metal of the pool and the progressively solidifying molten metal of the pool to refine the grain structure of the metal of the ingot being formed in a non-directional manner, and effecting the cooling and progressive solidification of the molten metal of the pool within the mold cavity at substantially the rate at which it is fused-01f from the end of the electrode body.

6. A method as defined in claim 5 wherein the olfcentered relation of the end of the electrode body with respect to the horizontal section of the alloy metal pool is varied during the operation.

References @ited in the file of this patent UNITED STATES PATENTS 2,191,477 Hopkins Feb. 27, 1940 2,191,479 Hopkins Feb. 27, 1940 2,405,254 Hopkins Aug. 6, 1946 2,651,668 Southern Sept. 8, 1953 2,818,461 Gruber et al Dec. 31, 1957 2,858,586 Brennan Nov. 4, 1958 2,963,758 Pestel et al Dec. 13, 1960 2,978,525 Gruber et al. Apr. 4, 1961 3,067,473 Eopkins Dec. 11, 1962

Claims

3. IN APPARATUS FOR CONSUMABLE ELECTRODE FORMING A CAST SOLID-SECTION ALLOY METAL SUBSTANTIALLY CYLINDRICAL INGOT OF SUBSTANTIALLY UNIFORM AND FINER GRAIN STRUCTURE CORRESPONDING AT LEAST TO THE FINENESS OF A PRELIMINARILY FORGED BODY BY EMPLOYING A PREVIOUSLY FUSED VERTICALLYEXTENDING ALLOY METAL ELECTRODE BODY OF SUBSTANTIALLY THGE DESIRED METAL CONTENT OF THE SOLID ALLOY METAL INGOT, A MOLD HAVING A SOLID METAL INGOT FORMING VERTICAL MOLD CAVITY DEFINED BY A VERTICALLY-EXTENDING OUTER SIDE WALL AND A BOTTOM WALL COOPERATING THEREWITH, SAID MOLD CAVITY TERMINATING AT ITS UPPER END IN AN OPENING AND PROVIDING A FULLY HORIZONTALLY-CENTRALLY UNOBSTRUCTED METAL SOLIDFYING AND METAL MELTING AREA VERTICALLY UPWARDLY FROM SAID BOTTOM WALL, MEANS FOR COOLING SAID WALLS TO PROGRESSIVELY SOLIDIFY MOLTEN METAL UPWARDLY AND FORM A METAL INGOT OF SOLID SECTION FROM SAID BOTTOM WALL, MEANS FOR SUPPORTING THE ELECTRODE BODY ABOVE SAID MOLD CAVITY TO EXTEND THROUGH THE OPENING INTO AN OPERATING POSITION WITHIN SAID MOLD CAVITY, MEANS FOR SUPPORTING SAID MOLD FOR ROTATION ABOUT ITS CENTRAL AXIS, MEANS FOR CAUSING ELECTRIC CURRENT TO PASS THROUGH SAID ELECTRODE BODY FOR INITIATING AND MAINTAINING AN ELECTRIC CURRENT FLOW AT THE LOWER END THEREOF TO PROGRESSIVELY FUSE-OFF ALLOY METAL THEREFROM AND THEREBY CREATE AND MAINTAIN A MOLTEN ALLOY METAL POOL ACROSS THE FULL HORIZONTAL SECTION OF SAID MOLD CAVITY, MEANS FOR ADJUSTING AND MAINTAINING THE LOWER END OF SAID ELEC TRODE BODY IN A HORIZONTALLY OFFCENTERED RELATION WITH RESPECT TO THE HORIZONTAL SECTION OF SAID CAVITY AND THUS WITH RESPECT TO THE HORIZONTAL SECTION OF THE MOLTEN ALLOY METAL POOL, MEANS COOPERATING WITH SAID SUPPORTING MEANS FOR SAID ELECTRODE BODY FOR PROGRESSIVELY ADVANCING SAID ELECTRODE BODY TOWARDS THE MOLTEN METAL POOL TO MAINTAIN THE ELECTRIC CURRENT FLOW DURING THE MELTING OPERATION, MEANS FOR CONTINUOUSLY ROTATING SAID MOLD ABOUT ITS CENTRAL AXIS WITH RESPECT TO SAID SUPPORTING MEANS THEREFOR AND WITH RESPECT TO THE ELECTRODE BODY DURING THE ARC MELTING OF THE ELECTRODE BODY AT A RELATIVELY SLOW SPEED THAT PROVIDES BELOW AN EFFECTIVE CENTRIFUGAL FORCE WITH RESPECT TO THE MOLTEN METAL POOL AND IN SUCH A MANNER THAT THE MOLTEN METAL POOL IS MAINTAINED IN A SUBSTANTIALLY QUIESCENT CONDITION WITHOUT SURFACE EDDY CURRENTS THEREIN,SAID MEANS FOR ADJUSTING AND MAINTAINING THE ELECTRODE BODY IN A HORIZONTALLY OFF-CENTERED RELATION CARRYING SAID MOLD, AND MEANS CARRIED BY SAID SUPPORT MEANS AND COOPERATING WITH SAID ADJUSTING AND MAINTAINING MEANS TO LATCH SAID MOLD IN A SELECTED POSITION WITH RESPECT TO SAID ELECTRODE BODY.